The amount of weight a helicopter is capable of carrying is dependent on the amount torque the helicopter engine (or engines) is able to apply to the rotor shaft. The amount of torque a helicopter engine is able to apply to the rotor shaft at any particular time is known to change based on factors such as, for example, weather (e.g., temperature, wind, atmospheric pressure, humidity, precipitation, etc.), location, altitude, and/or other similar environmental conditions. As such, helicopters often include a torque sensor for detecting the amount of torque the engine(s) is/are presently are applying to the rotor shaft so that the amount of weight the helicopter is capable of carrying may be properly determined.
One type of torque sensor (e.g., a magnetostrictive torque sensor) generates a tensile voltage (Vt) and a compression voltage (Vc). The tensile voltage Vt represents stress in the tensile direction due to the torsional strain on the rotor shaft, and the compression voltage Vc represents stress in the compression direction due to the torsional strain on the rotor shaft. The amount of torque applied to the rotor shaft may then be inferred from these voltages in accordance with the following conditioning equation: (Vt−Vc)/(Vt+Vc).
In some helicopters, torque sensors may be located on or near the helicopter engine. As such, the accuracy of the torque sensor may be adversely affected by the amount of heat the engine generates. This is because, at least in part, some torque sensors, such as magnetostrictive torque sensors, are constructed with magnetically permeable material. As is known, the magnetic permeability of some materials is temperature dependant and so, therefore, may be the sum Vt+Vc. Specifically, as the permeability of the sensor material increases with temperature, Vt and Vc may also increase. An increase in both Vt and Vc increases the magnitude of the denominator in the conditioning equation (rather than remaining constant), which results in a decrease in the amount of indicated torque as temperature rises. Since the variations in torque sensor temperature from engine to engine are not controlled, variations in indicated torque may result.
Accordingly, it may be desirable to provide systems and methods for compensating a torque sensor based on the temperature of the rotor shaft. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.